WhatsApp Web is asking to update Chrome while using Chromium

The problem seems to be with the User agent Chromium for Linux is using right now. It is using Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) snap Chromium/71.0.3578.80 Chrome/71.0.3578.80 Safari/537.36 which WhatsApp web is recognizing as an older User Agent which Chrome used before version 36. I have also observed that the problem is with Chromium for Linux only since on the other hand WhatsApp web seems to work perfectly under Chromium version 71.0.3578.80 on Windows which uses User agent as Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3641.0 Safari/537.36.

So, to run WhatsApp web again you need to change the User Agent. Do remember to clear all cookies and temporary data to get these working since temporary data might create problems. There are two ways to change user agent:

1. Using Chromium Settings:

• Open New Tab and press Ctrl+Shift+I to open Developer Tools

• Click on Hamburger menu (vertical dots) and choose More tools - Network conditions

  

• Go to the Network conditions tab (should appear in bottom right), disable the option Select automatically and choose Chrome - Windows from drop-down menu.

  

• Note: You need to perform all things again once WhatsApp web is opened in new tab or Chromium is relaunched since Settings are applied only for that Tab and aren't remembered for a particular site.

2. Using an extension:

• Download and install User-Agent Switcher for Chrome
• This extension doesn't have any User agents for Chrome. So, you need to add a new custom User Agent or use in-built user agents, for example, Internet Explorer/Safari/Firefox.

• If you want to stick to "Chromium on Ubuntu" as User Agent:

  • Right Click (or two finger tap) on the extension in top bar and click on Options
  • A list will open which would look like

  

  • Click on New User-agent name. Give any name you like and as User-agent enter this Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/73.0.3683.75 Chrome/73.0.3683.75 Safari/537.36. Give group name as Chrome, in Append?, choose Replace and in Flag field enter New. Click on Add.

• Now, click on extension in top bar and change the UA to this newly created custom UA or some other UA (if not created).

  

• In this case UA is applied universally to all tabs.

Once you're done with one of the above ways, open WhatsApp Web to login.

Installing a browser extension IMHO is a bit overkill.
Instead, I've changed the Chromium icon in gnome to run the browser with --user-agent option.

• Close Chromium.

• Customize .desktop:

    cp /var/lib/snapd/desktop/applications/chromium_chromium.desktop ~/.local/share/applications
    vim ~/.local/share/applications/chromium_chromium.desktop
    # search "/snap/bin/chromium %U",
    # replace with "/snap/bin/chromium --user-agent='Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.183 Safari/537.36' %U"
  

• Then, reload Gnome:

  • Press Alt+F2
  • Enter restart and press Enter.

This trick worked for me. I use Version 81.0.4044.129 (Official Build) snap (64-bit)

Open url chrome://flags/#freeze-user-agent

Enable "Freeze User-Agent request header" option

once you relaunch browser, WhatsApp Web will open without problem.